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Solve, using cross - multiplication : ...

Solve, using cross - multiplication :
4x - 3y - 11 = 0
6x + 7y - 5 = 0

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To solve the system of equations using cross-multiplication, we start with the given equations: 1. \( 4x - 3y - 11 = 0 \) 2. \( 6x + 7y - 5 = 0 \) ### Step 1: Rewrite the equations in standard form We can rewrite the equations in the form \( ax + by + c = 0 \): - For the first equation: \[ 4x - 3y = 11 \quad \text{(Equation 1)} \] - For the second equation: \[ 6x + 7y = 5 \quad \text{(Equation 2)} \] ### Step 2: Identify coefficients From the equations, we identify the coefficients: - For Equation 1: \( a_1 = 4, b_1 = -3, c_1 = -11 \) - For Equation 2: \( a_2 = 6, b_2 = 7, c_2 = -5 \) ### Step 3: Apply the cross-multiplication formula The formulas for \( x \) and \( y \) using cross-multiplication are: \[ x = \frac{b_1 c_2 - b_2 c_1}{a_1 b_2 - a_2 b_1} \] \[ y = \frac{c_1 a_2 - c_2 a_1}{a_1 b_2 - a_2 b_1} \] ### Step 4: Substitute the values into the formulas Substituting the identified coefficients into the formulas: For \( x \): \[ x = \frac{(-3)(-5) - (7)(-11)}{(4)(7) - (6)(-3)} \] For \( y \): \[ y = \frac{(-11)(6) - (-5)(4)}{(4)(7) - (6)(-3)} \] ### Step 5: Calculate the numerator and denominator for \( x \) Calculating the numerator: \[ (-3)(-5) = 15 \] \[ (7)(-11) = -77 \] So, \[ b_1 c_2 - b_2 c_1 = 15 + 77 = 92 \] Calculating the denominator: \[ (4)(7) = 28 \] \[ (6)(-3) = -18 \] So, \[ a_1 b_2 - a_2 b_1 = 28 + 18 = 46 \] Thus, we have: \[ x = \frac{92}{46} = 2 \] ### Step 6: Calculate the numerator and denominator for \( y \) Calculating the numerator: \[ (-11)(6) = -66 \] \[ (-5)(4) = -20 \] So, \[ c_1 a_2 - c_2 a_1 = -66 + 20 = -46 \] Using the same denominator as before: \[ a_1 b_2 - a_2 b_1 = 46 \] Thus, we have: \[ y = \frac{-46}{46} = -1 \] ### Final Solution The solution to the system of equations is: \[ x = 2, \quad y = -1 \]
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